1. Field of the Invention
This invention relates to a diamond-containing body and more particularly such a body wherein the diamond is produced by chemical vapour deposition (hereinafter referred to as "CVD").
2. Discussion of the Background
Methods of depositing material such as diamond on a substrate by CVD are now well established and have been described extensively in the patent and other literature. Where diamond is being deposited on a substrate, the method generally involves providing a gas mixture which, on dissociation, can provide hydrogen or a halogen (e.g. F,Cl) in atomic form and C or carbon containing radicals and other reactive species (e.g. CH.sub.x, CF.sub.x wherein x can be 1 to 4). In addition oxygen containing sources may be present, as may sources for nitrogen, and for boron. In many processes inert gases such as helium, neon or argon are also present. Thus, a typical source gas mixture will contain hydrocarbons C.sub.x Y.sub.y wherein x and y can each be from 1 to 10 (e.g. CH.sub.4), halocarbons C.sub.x Y.sub.y hal.sub.z wherein x and y can each be from 1 to 10 and z can be from 1 to 3, or CO.sub.x, wherein x can be from 1 to 3, and optionally one or more of the following: O.sub.2, H.sub.2, N.sub.2, NH.sub.3, B.sub.2 H.sub.6, and an inert gas. Each gas may be present in its natural isotopic ratio, or the relative isotopic ratios may be artificially controlled. For example, hydrogen may be present as deuterium or tritium, and carbon may be present as .sup.12 C or .sup.13 C. Dissociation of the source gas mixture is brought about by an energy source such as microwaves, lasers, RF energy, a flame, or a hot filament, and the reactive gas species so produced are allowed to deposit on to a substrate and form diamond.
Layers of CVD diamond have been proposed as inserts for abrasive tools, particularly cutting tools. CVD diamond layers have found limited commercial favour for such applications. There are several reasons for this. First, CVD diamond, as with other diamond, is not easily brazeable to a tool holder. Second, when CVD diamond layers are bonded to cemented carbide substrates to improve the brazeability thereof, they tend to laminate or flake in use and this is unacceptable.